Šimunović Luka, Miličević Ana Marija, Brenko Luka, Haramina Tatjana, Meštrović Senka
Department of Orthodontics, School of Dental Medicine, University of Zagreb, Zagreb, Croatia.
Department of Orthodontics, School of Dental Medicine, University of Zagreb, Zagreb, Croatia.
Am J Orthod Dentofacial Orthop. 2025 Oct;168(4):466-476. doi: 10.1016/j.ajodo.2025.04.022. Epub 2025 May 14.
The mechanical performance and fit of orthodontic aligners are influenced by their interaction with moisture in the oral environment. This study aimed to evaluate and compare the water absorption, desorption kinetics, and diffusion behavior of thermoformed (Invisalign [Align Technology, Santa Clara, Calif] and ClearCorrect [Institut Straumann AG, Basel, Switzerland]) and 3-dimensional (3D)-printed (Tera Harz TC-85, Clear A; Graphy Inc, Seoul, South Korea) orthodontic aligners.
Thirty-two aligners were divided by brand and fabrication method. The samples were immersed in distilled water at 37°C for 14 days and weighed daily. Desorption was measured at hourly intervals for 8 hours and once at 24 hours after removal from immersion. Diffusion kinetics were modeled using log-log transformed data and linear regression based on the Fickian diffusion theory.
All materials followed Fickian diffusion profiles. Thermoformed aligners showed significantly higher water absorption than 3D-printed aligners by day 14 (4.91% for Invisalign vs 2.76% for Clear A; P <0.001). Invisalign also exhibited the highest diffusion slope (k = 0.74) and the fastest desorption (93.7% in the first hour). Three-dimensional-printed aligners displayed slower early desorption but reached comparable release at 24 hours. A strong correlation was observed between water absorption and early desorption (r = 0.903; P <0.001).
The aligner fabrication method and material composition significantly affected the moisture kinetics. Thermoformed aligners, especially those with outer thermoplastic polyurethane layers, demonstrate greater and faster water interactions, whereas 3D-printed aligners offer lower overall uptake but delayed release. These differences may influence the aligner fit and performance in clinical settings.
正畸矫治器的机械性能和贴合度会受到其与口腔环境中水分相互作用的影响。本研究旨在评估和比较热成型（隐适美[Align Technology公司，加利福尼亚州圣克拉拉]和ClearCorrect[士卓曼集团，瑞士巴塞尔]）和三维（3D）打印（Tera Harz TC - 85，Clear A；Graphy公司，韩国首尔）正畸矫治器的吸水、解吸动力学及扩散行为。
32个矫治器按品牌和制作方法分组。将样本在37℃蒸馏水中浸泡14天，每天称重。取出浸泡样本后，每小时测量8小时的解吸情况，并在24小时时测量一次。基于菲克扩散理论，使用对数-对数转换数据和线性回归对扩散动力学进行建模。
所有材料均符合菲克扩散曲线。到第14天，热成型矫治器的吸水量显著高于3D打印矫治器（隐适美为4.91%，Clear A为2.76%；P<0.001）。隐适美的扩散斜率也最高（k = 0.74），解吸速度最快（第一小时为93.7%）。3D打印矫治器早期解吸较慢，但在24小时时达到类似的释放量。观察到吸水量与早期解吸之间存在强相关性（r = 0.903；P<0.001）。
矫治器制作方法和材料成分显著影响水分动力学。热成型矫治器，尤其是那些带有外部热塑性聚氨酯层的，表现出更强且更快的水分相互作用，而3D打印矫治器的总体吸水量较低但释放延迟。这些差异可能会影响矫治器在临床环境中的贴合度和性能。
